In the wind power industry there is a tendency to produce wind turbines of increasing size, whereby the size of the individual parts of the wind turbines also increase. Traditionally, electrical power is transferred from the nacelle to the rotor by use of a slip ring as the rotor is rotatably connected to the nacelle. Thus, the slip ring can be used to transfer electrical power from the stationary nacelle to the rotating rotor. Due to the increasing size of the wind turbine, the slip ring needs to be of a considerable size.
Furthermore, the slip ring may be exposed to heavy wear and may thus need regular maintenance or even replacement. Moreover, the slip ring may not always provide sufficiently good contact for transfer of high power current.